The Effect of the Substrate on the Conductivity of NiO Electrodes in Electrochemical Capacitor Shaped by Electrophoretic Deposition

Abstract

In order to study the effect of the substrate on the electrochemical performance of pseudocapacitor electrodes, NiO nanoparticles have been deposited by EPD on different substrates, such as Ni foams and Ni, Cu and stainless steel foils. The electrochemical impedance spectroscopy was used to determine the electron charge-transfer resistance as well as the ion-diffusion resistance of the different substrate/coating systems. Lower charge-transfer resistance and higher ion-diffusion rates were measured when Ni foils are used as substrate or collector. That means NiO/Ni foil system has the highest charge-transfer and the best electrolyte accessibility, which is an evidence of the excellent electrochemical performance of the semiconductor coating and the metallic substrate. On the other hand, the shape of the electrode has been also studied because it is strongly related with the ion-diffusion rate. Although the Ni foams have a larger specific surface area, their charge-transfer resistance results higher than in foil substrates.